US1910876A

US1910876A - Rotary pump

Info

Publication number: US1910876A
Application number: US575088A
Authority: US
Inventors: Appel Daniel
Original assignee: GLENN B CARMAN; LE ROY A WESTMAN
Current assignee: GLENN B CARMAN; LE ROY A WESTMAN
Priority date: 1931-11-14
Filing date: 1931-11-14
Publication date: 1933-05-23
Anticipated expiration: 1950-05-23

Description

D. APPEL ROTARY PUMP Filed Nov 14, 1931. 4 Sheets-Sheet 1 .FHNIE'L HPPEL D. APPEL ROTARY PUMP May 23, 1933.

Filed Nov. 14, 1931 i 4 Sheets-Sheet 2 4 Sheets-Sheet 3 D. APPEL ROTARY PUMP Filed Nov. 14,

May 23, 1933.

May 23, 1933-. APPEL 1,510,376 ROTARY P UMP Filed Nov. 14. 1951 4 Sheets-Sheet 4 risn .vnma'z. IIFPEL INVENTOR I ATTCRNEY 1,853,394 dated April 12, 1932,.in which a stone, which are reciprocated by a crank Patented May 2 3, 1933 UNITED STATES PATENT OFFICE DANIEL APPEL, OF EAST CLEVELAND, OHIO, ASSIGNOR TO LE ROY A. WEST'MAN AND GLENN 1B. CARMAN, BOTH OF CLEVELAND, OHIO nanny rum? Application filed November '14, 1931.

This invention relates to rotary pumps of the type described in my Letters Patent No.

rotatable cylinder or rotor is mounted in a casing and carries and supports a set of-pisshaft or eccentrics in offset relation with respect to the axis of the rotor andtransfer the rotary movements thereof to the rotor.

I have found that these pumps, in which each stroke of the pistons corresponds to half a revolution of the rotor and to a complete revolution of the crank shaft or eccentrics, work satisfactorily only when certain definite relative dimensions of the rotor diameter and the piston strokes are maintained, the latter being in turn governed by the crank shafts or eccentrics;

The general object of the presentinvention is to define such relations and the limits withinwhich practical results may be obtained from a rotary pump of the type described. I have found that the relationship between the rotor diameter of the pump and the piston stroke must fall approximately above ratios 3 ,to land that pumps of highest efliciency should, have approximately between 4.3 to 1' and 6 to 1. The limitations in the ratios described above are necessary for the followin reasons.

Pumps of the ind described, when rotated at low speeds, do not work with uniform pressure as the movement of thepistons dur- V ing each revolution of the cylinder is variable. In order to overcome such disadvantages and to produce a uniform pressure at the outlet side of rotary pumps it is necessary to run the same with high speed, at

least over two hundred revolutions per minute. Such speed of the rotor of course increases the amount of liquid discharged and necessitates a decrease of the cross section of the piston, in order to avoid twisting of the crank shaft. Any decrease in the cross section of the piston of course decreases the necessary bearing between piston and crank shaft and makes pumps with ratios below 3 to 1 impractical, and useless, particularly smaller pumps with a rotor diameter below 3 inches. I

Serial No. 575,088,

Pumps with higher ratios, say beginning with approximately above 7 to 1 become more and more inelficient because of marked binding tendency between the pistons andthe rotor. ,Thus, with higher ratios between rotor diameter and piston stroke the distance between the axis of the rotor and the axis of the crank shaft and therewith the leverage of the crank shaft tending to rotate the rotor shortens, to such an extent that substantially higher driving power is required.

This increase in driving power increases the friction between the pistons and their chambers so that the force required to rotate for use in the oiling systems of aeroplanes,

refrigerating plants, etc.

The invention will better be understood 1 from thefollowing description of a-rotary pump and the diagrams shown in the aplongitudinally of a pump of the described type, excepting the shaft which is shown in elevation. Fig. 2 i s an end elevation ofa pump with the end plate or cover removed, and Fig. 3 a vertical section of the pump on line 3-3 of Fig. 1. Fig. 4 is a similar sectional view on line 4-4 of Fi 1. Fig. 5 is a sectional view of a modi ed form of pump, embodying the invention, and Figs. 6 and 7 p are side and end elevations of the rotatable cylinder or rotor of the pump shown in Fig. 5. Fig.8 is a side view of the drive shaft and Figs. 9 and 10 are elevations of the separate pistons actuated by the drive shaft. Fig. 11 is asectional view of a pump of the type shown in Figs. 5 through 10 provided with a splitrotor. Fig. 12 is a sectional View of the rotor and Fig. 13 a side view of the split rotor. Fig. 14 is a side view of the drive shaft, and Figs. 15 and 16 elevations of the separate pistons actuated by the drive shaft. Fig. 17 is a diagrammatical view showing the change of leverage during one As delineated in Figs. 1 through 4, the

pump comprises a cylindrical 'body 2 containing a circular chamber 3. One end of this chamber is closed by an integral wall of the casing, and the opposite end by a removable head or plate 4, or both ends of the casing may be rovided with removable heads if desired. eparate inlet and outlet ports or passages 5 and 6, respectively, are provided within body 2 at opposite sides of circular chamber 3, each port extending circumferentially of the chamber for a substantial distance, say approximately ninety degrees, thereby leaving a closed area of approximately the same are at the top and bottom of the chamber between the two ports. A shaft 7 extends through body 2, one end having rotatable bearing within plate 4 where a hollow gland member 8 and packing materials are provided to prevent leakage. Gland member 8 is filled with a lubricant, and a certain degree of suction is produced inthis pump which feeds the lubricant to the working parts through suitable ducts or passages 9 inthe shaft. The opposite end of shaft 7 extends through a second gland member 10 fastened by screws or bolts 11 to body 2, and a drive pulley or gear (not shown) may be fastened to the exposed end of the shaft; or any drive coupling may be used. Two circular eccentrics 12-12 form integral parts of shaft 7 where they may revolve in separate orbits side by side within circular chamber 3L These eccentrics are one hundred and eighty degrees apart, the centers being equally distant from the axis of the shaft, which is offset or eccentricallyrelated to the axis or center .of circular chamber 3. The degree of offset or eccentricity of shaft 7 to the center of chamber 3 is exactly one-half ofthe radius of orbital travel of each eccentric 12-12'. As a result the circular orbit of each eccentric 12-12, as defined by the center of the eccentric, touches the axis or center of circular chamber 3. This relationship of parts is essential, otherwise rotatable movement of the rotor member 14, as hereinafter described, cannot occur.

Rotor member 14 is cylindrical and rotates Within chamber 3 with a close fit at its circumference and its opposite ends. The center of its rotative movement is therefore the axis or center of chamber 3. Rotation is imparted to rotor member 14 by both eccentrics 12 12 when power is applied to revolve shaft- 7. A pair of power translating elements, herein also referred to as pistons, 1515 respectively, are rotatably connected or coupled to the eccentrics 1212. Thus, each' piston has a circular opening therein within which its eccentric fits, the opposite ends of the piston being curved or rounded in the same degree as circular chamber 3, although not necessarily. The piston may be either a flat bar or block, as shown in Figs. 1 through 4, or it may be of cylindrical form. This piston embodies two parallel straight sides or edges equally distant from the center of the bushed opening therein. Rotor member 14 is formed with two straightsided channels 16-16 extending diametrically across the flat end faces thereof, and lie at right angles, or in other words, are quartered in respect to the circle. Piston 15 within channel 16 is shown at one end of its stroke. Also, the two eccentrics 12-12 are centered in the same vertical plane as the center of rotatable member 14, and in that relationship of parts take note that the center of circular eccen tric 12 is co-incident with the center or axis of rotor member 14. This is a dead center position for that piston and rotor member 14 wherefor in the absence of a second eccentric differently positioned, a binding or looking action would take place, thereby either preventing or interfering with the free rotation of rotor member 14. In connection with the foregoing also observe that each eccentric is circular and can only revolve within the circular opening in the piston with which it is coupled, and that no slot is used in the piston to permit other play or movement between the eccentric and the piston.

In operation, when shaft .7 is rotated the two eccentrics 1212"co-act with the two pistons 15 15 to revolverotor member 14. Two revolutions of the shaft are required to produce one revolution of the rotor member. The pistons are carried around with the rotor member and are moved back and forth within their respective channels or working chambers by the eccentrics, each single revolution of the rotor member producing a forward stroke and a return stroke of the pistons.

' circular wall of a casing. The revoluble shaft and its eccentrics produce such oscillatory movement of the pistons. In addition the pistons are carried around by the rotor in an orbit eccentric to the circular wall of the cas- The relative proportions of the working parts of the rotary pumps described herein must come within certain limits, in order to produce a practical and eflicient structure. Thus, the ratio of the diameter of the rotor 03 to the length of the piston stroke 1 should be equal to or above3to1as best understood from diagrams of Figs. 17 through 19. The dlagram of Fig. 19 shows the change of leverage for pumps of different ratios, that is, pumps having a ratio of 3 to 1, 6 to 1, and 12 to 1.

It will readily be seen that a decrease of the piston stroke causes a decrease in the size of the eccentrics and that a pump with a ratio.

lower or substantially lower than 3 to 1 is impractical because of the decreased bearing for the eccentric, which bearing becomes too 'small to withstand the heavy wear incident to continuous use of the pump and because of the heavy shocking and hammering action of the pistons, which is increased with increasing piston stroke and increased speed of the pistons.

In pumps with ratios say about 10 to 1, the leverage applied to the rotor for rotating same has decreased to such an extent that the necessarily increased driving power begins to tilt the pistons and rotor within the limits of their clearance (the clearance between rotor and rotor housingand pistons and piston chamber) thereby effecting substantial friction and finally binding between the pistons and their chambers so that the pump becomes inoperative. The binding action of the pistons depends of course upon'the pressure present at the outlet side of the pump.

In the modified form of pump shown in Figs. '5 to 10, the same characters used in Figs. 1 to 4, in-- asmuch as the working parts are related and operate in the same ,way, anddiffer only in shape and form. Thus, the casing is of greater length, and the rotor member is an elongated cylindrical body instead of a flat disk. This cylinder is not channeled at its ends but is formed instead with a pair of circular openings or

chambers

18, 18 spaced apart and extending at right angles. diametrically through the body. Accordingly,-

.structure is shown in Fi like parts are designated by' ly,the previously mentioned binding action of the pump is not avoided.

In pumps of the t pe described it is necessar that the central opening 22 be contmu ous y covered by the pistons and never openly exposed so that a flowing ofllquld from one cylinder chamber into the other cannot take place. This necessity renders it 1mpossible to build a structure as shown in Fi s. 5 through 10 with a ratio below 5 to 1, as t e assembly of the rotor with its pistons can only .be accomplished by axially shifting the drive shaft 7 through central opening 22 of the rotor and the circular openings in pis tons 19-19. To permit such assembly proceedings central'opening 22 must be of such cross section that the drive shaft 7 with eccentrics 12-12 may readily be rotated therein. Furthermore, the lateral distance between the piston chambers must be approximately equal to the piston diameter to permit rotation of the drive shaft into proper alignment of its eccentrics with respect to the circular openings of pistons 1-9-19' after one of the eccentrics has been shifted through the circular opening of one of the pistons. Consequently, pumps with a ratio below 5 to l-mu st be provided with an opening of such size that the reciprocatory pistons do not.

continuously cover same and, are. therefore impractical.

The structure of Figs. 5 through 10 has a ratio of approximately 6 to 1. In'order to build pumps of this type with a ratio below 5 to 1 the rotor must be split to enable assembly with a smaller central opening. ,Such gs. 11 through 16 in which like parts are designated by the same characters used in Figs. 1"to' 4. As shown, the rotor member of this structure, an elongated cylinder embodies two

inter-connected parts

23 and 24;,each ofwliich is formed with a circular opening or

chamber

25, 25 respectively. These parts, 23 and 24, are interlocked against lateral central extension 28 of face 26' of part 24.

simultaneously align

parts

23, 24 by means of dowel portions 30. The axial opening 31 of the assembled rotor is equal in cross section to the .size of the eccentrics 12-12 of the drive shaft and permits building of such pump with ratios of 3 to 1 without exposing the central-opening during the reciprocatory movements of the pistons.

Q viously, the dimensions of the machine may also be changed and more than two pistons employed in av single rotor member b merely extending the length of the cylindrimovement. Thus, the face 26 of: part 23 is recessed and surrounds -w1th its circumferential flange portion 27, a

cal casing and rotor member, and duplicating the parts. Roller or ball bearings may be used, and other modifications.

What I claim, is:

1. A rotary pump having a cylindrical casing, a rotor within said casing having a central bore extending longitudinally through said rotor, a series of chambers within said rotor diametrically thereof and closely and angularly related to each other, a piston for each of said chambers and integral rotatable driving means eccentrically mounted with respectto the axis of said rotor including enlarged eccentric portions angularly related to each other and coupled with said pistons centrally thereof, the eccentricity of said driving means with respect to said axis of said rotor being such that the ratio of the rotor diameter to the piston stroke of said pistons is above 3 to -1 and said rotor being made in separate interconnected sections, axially aligned with each other, and each of said sections including a piston chamber to permit assembly of the rotor, pistons and driving means.

2. A rotary pump having a cylindrical casing, a rotor within said casing having a central bore extending longitudinally through said rotor, a series of chambers within said rotor diametrically thereof and angularly related to each other, a piston for each of said chambers and integral rotatable driving means eccentrically mounted with respect to the axis of said rotor includingenlarged eccentric portions fitting said central bore and angularly related to each other and coupled with said pistons centrally thereof, said adjoining chambers in said rotor being spaced :1 distance equal to their cross section to permit assembly of said rotor, pistons and drive shaft with the small central bore through said rotor.

In testimony whereof I affix my signature.

DANIEL APPEL.